1. Field of the Invention
The present invention relates to a photoelectric conversion device, an image sensing system, and a method of manufacturing the photoelectric conversion device.
2. Description of the Related Art
MOS photoelectric conversion devices that use MOS transistors are under vigorous development as the latest in photoelectric conversion devices. In such photoelectric conversion devices, the pixel size decreases as the number of pixels increases. As the pixel size decreases, both the opening area of a wiring layer and the area of the light-receiving surface of a photoelectric converter (for example, a photodiode) in each pixel, in turn, is reduced, which could degrade the sensitivity of the photoelectric converter. Hence, an interlayer lens, which functions as a lens for suppressing degradation in sensitivity of the photoelectric converter, is often formed between the photoelectric converter and an on-chip lens. Also, because the thickness of a wiring layer is limited by the process rule, the aspect ratio of the opening of the wiring layer inevitably rises.
Japanese Patent Laid-Open No. 2000-150846 discloses an arrangement that improves the focusing efficiency of an on-chip lens by forming an interlayer film of a photoelectric converter to be thinner than an interlayer film including a passivation film of peripheral circuitry so that a light-receiving unit and the on-chip lens have a short distance between them. However, Japanese Patent Laid-Open No. 2000-150846 proposes no method of manufacturing an interlayer lens.